Alert archive / Illinois / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 80, NWS Quad Cities, IA

August 11, 2021Des Moines County, Louisa County, Iowa; Henderson County, Mercer County, Warren County, Illinois

NWS Quad Cities, IA issued this severe thunderstorm warning at Aug 11, 2021, 6:38 AM CDT for Des Moines County, Louisa County, Iowa; Henderson County, Mercer County, Warren County, Illinois. It was in force for 37 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 11, 2021, 6:38 AM CDT (11:38 UTC)
Expired: Aug 11, 2021, 7:15 AM CDT
In force: 37 min
Issued by: NWS Quad Cities, IA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 50.0 mph

Counties Des Moines County, IA, Louisa County, IA, Henderson County, IL, Mercer County, IL, Warren County, IL

The radar

The Quad Cities radar (KDVN), 65 km from the middle of the area, began a volume at 11:38 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

Time	Report	Where	Remark
Aug 11, 6:43 AM CDT	TSTM WND DMG	Keithsburg, IL	SMALL TREE LIMBS AND BRANCHES DOWN AROUND TOWN...TIME ESTIMATED FROM RADAR. DELAYED REPORT.
Aug 11, 6:44 AM CDT	TSTM WND DMG	New Boston, IL	STRUCTURAL DAMAGE TO A ROOF, LOST POWER. TIME ESTIMATED FROM RADAR. DELAYED REPORT.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 11.6 hours before the alert went out and 69 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 856 J/kg
Mixed-layer CIN: -155 J/kg
Mixed-layer LCL: 940 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 77 m²/s²
0-3 km storm-relative helicity: 160 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -1.4

Open this sounding in Storm Lab

The text

As transmitted.

887 
WUUS53 KDVN 111138
SVRDVN
ILC071-131-187-IAC057-115-111215-
/O.NEW.KDVN.SV.W.0080.210811T1138Z-210811T1215Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Quad Cities IA/IL
638 AM CDT Wed Aug 11 2021

The National Weather Service in the Quad Cities has issued a

* Severe Thunderstorm Warning for...
  Northeastern Henderson County in west central Illinois...
  Northwestern Warren County in west central Illinois...
  Western Mercer County in northwestern Illinois...
  Northeastern Des Moines County in southeastern Iowa...
  Southeastern Louisa County in southeastern Iowa...

* Until 715 AM CDT.

* At 637 AM CDT, a severe thunderstorm was located over Oakville, or
  9 miles southeast of Wapello, moving east at 40 mph.

  HAZARD...Quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Damage to vehicles is expected.

* This severe thunderstorm will be near...
  Keithsburg around 645 AM CDT.
  Joy around 650 AM CDT.

Other locations in the path of this severe thunderstorm include
Millersburg, Seaton, Aledo and Burgess.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
sturdy building.

&&

LAT...LON 4097 9115 4119 9114 4129 9066 4102 9057
TIME...MOT...LOC 1137Z 258DEG 36KT 4108 9105 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...<50 MPH

$$

DC

3 follow-up statements

117 
WWUS53 KDVN 111147
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
647 AM CDT Wed Aug 11 2021

ILC071-131-187-IAC057-115-111215-
/O.CON.KDVN.SV.W.0080.000000T0000Z-210811T1215Z/
Henderson IL-Warren IL-Mercer IL-Des Moines IA-Louisa IA-
647 AM CDT Wed Aug 11 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 715 AM CDT
FOR NORTHEASTERN HENDERSON...NORTHWESTERN WARREN...WESTERN MERCER...
NORTHEASTERN DES MOINES AND SOUTHEASTERN LOUISA COUNTIES...

At 647 AM CDT, a severe thunderstorm was located over Keithsburg, or
11 miles southwest of Aledo, moving east at 40 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

This severe storm will be near...
  Joy around 650 AM CDT.
  Millersburg and Seaton around 655 AM CDT.

Other locations in the path of this severe thunderstorm include
Little York, Aledo and Burgess.

LAT...LON 4100 9109 4121 9103 4129 9066 4102 9057
TIME...MOT...LOC 1147Z 258DEG 36KT 4110 9092 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

DC

213 
WWUS53 KDVN 111157
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
657 AM CDT Wed Aug 11 2021

IAC057-115-111206-
/O.CAN.KDVN.SV.W.0080.000000T0000Z-210811T1215Z/
Des Moines IA-Louisa IA-
657 AM CDT Wed Aug 11 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN DES MOINES AND
SOUTHEASTERN LOUISA COUNTIES IS CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

LAT...LON 4104 9094 4107 9095 4110 9095 4111 9096
      4123 9094 4129 9066 4102 9057
TIME...MOT...LOC 1156Z 258DEG 36KT 4112 9080 

$$

ILC071-131-187-111215-
/O.CON.KDVN.SV.W.0080.000000T0000Z-210811T1215Z/
Henderson IL-Warren IL-Mercer IL-
657 AM CDT Wed Aug 11 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 715 AM CDT
FOR NORTHEASTERN HENDERSON...NORTHWESTERN WARREN AND CENTRAL MERCER
COUNTIES...

At 656 AM CDT, a severe thunderstorm was located over Seaton, or near
Aledo, moving east at 40 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

This severe storm will be near...
  Aledo around 705 AM CDT.

Other locations in the path of this severe thunderstorm include
Burgess.

LAT...LON 4104 9094 4107 9095 4110 9095 4111 9096
      4123 9094 4129 9066 4102 9057
TIME...MOT...LOC 1156Z 258DEG 36KT 4112 9080 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

DC

278 
WWUS53 KDVN 111206
SVSDVN

Severe Weather Statement
National Weather Service Quad Cities IA/IL
706 AM CDT Wed Aug 11 2021

ILC071-131-187-111216-
/O.EXP.KDVN.SV.W.0080.000000T0000Z-210811T1215Z/
Henderson IL-Warren IL-Mercer IL-
706 AM CDT Wed Aug 11 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN HENDERSON...
NORTHWESTERN WARREN AND CENTRAL MERCER COUNTIES WILL EXPIRE AT 715 AM
CDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.

LAT...LON 4104 9094 4107 9095 4110 9095 4111 9096
      4123 9094 4129 9066 4102 9057
TIME...MOT...LOC 1206Z 258DEG 36KT 4114 9070 

$$

DC

The office that day

Everything else NWS Quad Cities, IA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 11, 5:38 AM CDT	Special Weather Statement	DVN	Lee	37 min
Aug 11, 5:56 AM CDT	Severe Thunderstorm Warning	DVN	Des Moines, Lee	19 min
Aug 11, 6:10 AM CDT	Severe Thunderstorm Warning	DVN	Des Moines, Henry, Lee	20 min
Aug 11, 6:24 AM CDT	Severe Thunderstorm Warning	DVN	Des Moines	22 min
Aug 11, 6:59 AM CDT	Flash Flood Warning	DVN	Des Moines, Lee	3 hr
Aug 11, 7:04 AM CDT	Special Weather Statement	DVN	Muscatine	26 min
Aug 11, 8:16 AM CDT	High Wind Warning	DVN	Clinton, Des Moines, Louisa, Muscatine, Scott	104 min
Aug 11, 9:46 AM CDT	Areal Flood Warning	DVN	Des Moines, Lee	3 hr
Aug 11, 10:24 AM CDT	Special Weather Statement	DVN	Lee	21 min
Aug 11, 3:36 PM CDT	Special Weather Statement	DVN	Washington	24 min
Aug 11, 4:26 PM CDT	Severe Thunderstorm Warning	DVN	Delaware, Dubuque	49 min
Aug 11, 5:11 PM CDT	Severe Thunderstorm Warning	DVN	Delaware, Dubuque, Jackson, Jones	49 min
Aug 11, 5:38 PM CDT	Tornado Warning	DVN	Dubuque	13 min
Aug 11, 6:24 AM CDT	Special Weather Statement	DVN	McDonough	36 min
Aug 11, 7:32 AM CDT	Special Weather Statement	DVN	Rock Island	28 min
Aug 11, 7:55 AM CDT	Special Weather Statement	DVN	Bureau, Henry, Whiteside	65 min
Aug 11, 8:07 AM CDT	Severe Thunderstorm Warning	DVN	Bureau, Henry, Rock Island, Whiteside	53 min
Aug 11, 8:33 AM CDT	Severe Thunderstorm Warning Considerable damage threat	DVN	Bureau, Putnam, Whiteside	57 min
Aug 11, 9:59 AM CDT	Special Weather Statement	DVN	McDonough	31 min
Aug 11, 10:45 AM CDT	Special Weather Statement	DVN	Henderson, Warren	30 min
Aug 11, 10:57 AM CDT	Severe Thunderstorm Warning	DVN	Henderson, McDonough, Warren	33 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2021 Severe Thunderstorm Warnings in Iowa, 2021 Every severe thunderstorm warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.